Piston and method of making the same.



E. W. CLARK,

PISION AND METHOD OF MAKING THE SAME.

APPLICATION FILED OCT. 13 19W.

Patented m. 15, 1918.

R O T N E V N I has, "P

nil-nil EISTGN A2323 METHOD 0'32 IFAKIWG THE- SAFE 2E.

Application filed Detober 18, 193.7.

To all whom it may} concern:

Be it known that l, EDWARD W. CLARK, citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of'tfalifornia, have invented new and useful improvements in Pistons and lilet-hod of Making the Same, of which the following is a specification.

lily invention relates primarily to pistons for internal combustion engines, but the same may be used in connection with stean'i engines as Well with a like degree of snccess and ellioieney, the novelty of my iniprorements including a piston having; a skirt portion of cast iron, preferably, so formed that a minimum thickness may be provided and the major portion thereof being machined for providing a minimum Weight, without detracting from the chiciency of the piston.

In order that the above objects may be carried out it is necessary that the head of the piston should be separately formed and attached to the skirt portion, bot-h omls of the skirt being open and access being thus afforded to the interior th root 5. r machining the inner periphery or" the skirt, which, in the ordinary form of piston is inaccessible for this purpose.

The head and skirt being separately formed, may be made of separate materials, the skirt, as stated, being preferably of cast iron, and the head of steel, thus rendering the head capable of being turned, down to a very thin cross section and yet providing ample strength and resistance to the impact of the explosions in the engines.

A further object of this invention is to provide means for reinforcing the head and for securely attaching the same to the skirt subsequent to the separate finishing of these elements, so that a permanent union of the two parts may be made.

I am aware that patents have been heretofore granted for pistons having separable and detachable heads of different material from that used in the skirt portion, one form of such device being disclosed in a former invention of mine for which I have made application for Letters Patent of the United States, filed November 18, 1915 Serial Number 62,137, and allowed August. 29. 1916; a patent therefor having been granted to me on April 3, 1917, Number 1,221,419. The present invention, however, is an im provement over my former invention, the

Specification of Letters Patent.

w J @61 in. J]

Patented Serial l lo. 197,348.

several features of which *ill be. hereinafter set forth and described in detail.

Having in mind the above and other obects, prefer to carry out the obiects men tioned by means of structure illustra ed in the accoiniimuyin drawings. in which:

Figure l. is a plan of my iiiiproretl. piston, partly bro n away at the top;

Fig. 2 is bottom view or" the same.

3 is an elevation of the same. na or portion of which in section on a plane longitudinally of the Wrist pin.

Fig. 42 an elevation, partly in section trans\ ersely of the wrist pin and at right angles to Fig. 3. V

Fig. is a perspective view of the "sistehead, in inverted position.

Similar characters of. reference are einployeclthroughout the specification followng and in the several views oit the draWinzZs touindicatinp the same and like parts. L

ihe preferred embodiment of: my ini proved piston which i. shown in th was or 7 normally open at enus tor ah'ording access to the interio oi? the piston for a i'inishinn tool, and a 3)- rate head 11 which adapted to be iir serted in the upper end the skirt s2 l qnent to the finishing operation and permanently hold therein in the manner he sinafter described. The general ap 1 of the skirt 10 is siinilzmto that oi pistons in general use in internal combustion nines, with the exception that the u r and lower ends thereof provided hilt-l1 a. greater thickness of metal than the central portion, indicated at 12 and 13, and a pair of transve 'sely disposed internal and oppositely formed bosses 14k and 15 are cast integrally With the skirt for receiving a Wrist pin 16. Bores. 17 are formed in lihe bosses 14- and 15 to fit the Wrist pin as in the usual and a connecting rod 18 may be pivotally held on the wrist win by means of a bushing 19, as shown in Fig. 3. i

The skirt 10 is preferably formed of cast iron or" a hi h grade, this beingthe best metal for general use in cylinders, and as stated, the skirt is integrally cast with the walls thereof of about a uniform thiclrn after which the skirt may be turned down in a lathe to a minimum thickness as shown. thus reducing the Weight of the piston to cross section and extend upwardly in the skirt 10 to a point near the top where a circular rib 22 is formed and a transverse rib 23 connects the same with a central boss 24. The ribs 20, 2 1, 22 and 23 and the boss2 l are integral with the skirt 10 and serve as a.

support for the head 11, which I will now describe.

The head 11 is of cup formation with a web portion 25 forming a top and a circular side 26 adapted to have threads 27 formed thereon so that the same may be threaded into the upper end of the skirt 10 in an inverted position as shown in the drawing,

over this shoulder so as to rigidly clench the head and hold the same in position firmly between the rib 22 andshoulder 28. Ordinary piston rings 29 are positioned in the usual. grooves formed on the exterior of the piston skirt, as shown.

It will be understood from the description of the -structure of my device. that the head 11 being formed preferably of steel may be made in a single stamping operation of an integral sheet of steel, and by means of the open ends of the skirt 10 a turning tool may be easily inserted in each end of the skirt for reducing and finishing the walls of 'the pis ton to a minimum thickness, thus providing'a minimum weight and increasing the eiliciency of the piston. The central portion of the skirt, as shown, may be turned down on the outside instead of the inside for providing substantially a uniform thickness of metal to compensate for the finishing of the inside at the end portions.

It will be also understood that the head 11, when clenched in the skirt as described, will be practically integral with the skirt and by means of the supporting ribs formed integral with the walls of the skirt additional supports will be provided at points near the center of the skirt for reinforcing thehead against damage or deflection due to shock from successive explosions. If found to be desirable or necessary, the web of the head may be riveted to the boss connected to the circular rib 22 so that no bending or warping may result from continual use. The space around the vertical-ribs in the skirt will be ample to permit the insertion and'use of a tool for finishing the interior of the walls. The original skirt casting should be sufficiently thick to permit the turning off of surplus grain from the metal so that no defects will be left in the casting and a true circle may be preserved under all strains in the walls. The positions of the vertical supporting ribs relative to the walls of the skirt serve to equalize the strain on the wrist pin under all conditions, and thus prevents excessive wear on the pin and connecting rod bearings. Other advantages will be apparent.

What I claim is:

1. A piston comprising a composite structure including a skirt open at both ends and threaded to receive a head for closing the working end thereof, and a head threaded into said skirt and having its edges formed over and in permanent contact with an abutment on the interior of said skirt.

2. A two-piece piston comprising a cast iron skirt having anepening at both ends,-

the upper end thereof being threaded and a shoulder provided at the lower end of the threads, and a head having a web for closing. the working end of the piston and an extension adapted to be threaded into said skirt,

the end of. said extension being'formed over said shoulder.

3. A piston comprising separately formed skirt and head elements, said head being insertible in the working end of said skirt and the end thereof being formed over an abutment in said skirt, and a plurality of piston ring grooves being provided in said skirt element 4. A piston com-prising a separately forimed head and skirt, said head being insertible annular shoulder thereabove, said head havmg a threaded extension secured in said skirt and overlapping said shoulder.

7. A piston comprising separately formed head and skirt n'ienlbers, Said skirthaving integrally formed wrist pin bearings and means extending from said bearings for supporting said head. 7

8. A piston having separately formed head and skirt members permanently held together, said skirt having integrally formed wrist pin bearings and supporting ribs formed on said bearings for reinforcing said head.

9. A method of making pistons consisting of separately forming and finishing a head and a skirt member, internally threading one end of said skirt and externally threading said head for attachment together, providing an abutment internally of said skirt, and forming the inserted end of said head over said abutment.

10. A method of making pistons consisting of separately forming a head and a skirt of separate materials, threading the adjacent ends of said head and skirt for at taehment. together, said skirt having an 'annular shoulder formed therein, inserting said head into said skirt, and forming the end of said head over saidshoulder, for permanently holding said members together.

11. A method of making pistons consisting of separately forming a head and a skirt of different materials and attaching the same together for o ')eration, said skirt being open at the ends and having an annular shoulder therein near the end of said head,

and forming the inserted end f said head over said shoulder.

12. A piston comprising. .t-parately formed skirt and head members, said skirt member being open at both ends and having an integrally formed abutment at the working end thereof, and said head member being insertible in the end of said skirt member and adapted to rest upon said abutment.

- 13. A piston comprising separately'formed head and skirt members, said head member being insertible in and having its edges adapted to be formed over an abutment in said skirt member, and said skirt member having an integrally formed abutment for engagement with said head member.

14. piston comprising separately formed head and skirt members, said head member being insertible in the working end of said skirt member and said skirt member having means formed integrally therewith for holding said head member against invard movement and said skirt being recessed at the inner end of said head to prevent movement thereof outwardly of said skirt member. 15. A piston omprising separately formed head and skirt members, said head member being insertible in and serving to close the working and of said piston, and having its edges formed over a. shoulder on the interior of said skirt member, and said skirt member having an integrally abutment engaging the inner portion of said head member, said shoulder and said abutment servingto prevent the displacement of said head member from said skirt member.

EDWARD W. CLARK. 

